1. Field of the Invention
The present invention relates to an oral sustained-release preparation. More particularly, the present invention is concerned with an oral sustained-release preparation which contains at least one active ingredient selected from the group consisting of fasudil hydrochloride and a hydrate thereof, the preparation comprising at least one sustained-release coated particle comprising a core having a surface and a coating formed on the surface of the core, wherein the core contains the active ingredient and the coating comprises a coating base material and a specific insoluble auxiliary material, the preparation exhibiting a specific dissolution rate with respect to the active ingredient, as measured by the dissolution test. The present invention is also concerned with a method for evaluating an oral sustained-release preparation containing the active ingredient, the evaluation being conducted with respect to the sustained-release ability of the active ingredient.
By using the oral sustained-release preparation of the present invention, it becomes possible to surely control the release of fasudil hydrochloride from the preparation, so that a desired amount of fasudil hydrochloride is continued to be released from the preparation for a long period of time, and that the effect of fasudil hydrochloride is maintained for a relatively long period of time. Therefore, the frequency of the administration of the preparation becomes low, so that the burden of the patient who has to take the preparation can be decreased and the compliance with respect to the administration of the preparation can be improved. As a result, the therapeutic effect of fasudil hydrochloride is rendered reliable. Therefore, the oral sustained-release preparation of the present invention is extremely useful.
2. Prior Art
1-(5-Isdquinolinesulfonyl)homopiperazine hydrochloride (hereinbelow referred to as “fasudil hydrochloride”) has excellent vasodilative activity and is clinically used for treating cerebral vasospasm (which is likely to occur after the operation of a patient suffering from subarachnoid hemorrhage), cerebral ischemic symptoms accompanying the cerebral vasospasm, and the like, wherein the above-mentioned fasudil hydrochloride is used in the form of a parenteral preparation which is available under tradename “Eril Inj.” (registered trademark for the product produced and sold by Asahi Kasei Kogyo Kabushiki Kaisha, Japan) (see Unexamined Japanese Patent Application Laid-Open Specification No. 5-3851 (corresponding to U.S. Pat. No. 4,678,783)).
There are two conventionally known different types of crystals of fasudil hydrochloride, i.e., crystals containing no water of crystallization (hereinbelow referred to as “fasudil hydrochloride anhydride”) and crystals containing water of crystallization (hereinbelow referred to as “fasudil hydrochloride hydrate”) (see International Patent Application Publication No. WO97/02260 (corresponding to EP 0 870 767 A1)).